US Patent 7330197 Mixed reality exhibiting method and apparatus

In exhibition of a synthesized image which is obtained by synthesizing a virtual world image with a real world image observed from a viewpoint position and direction of a user, data representing a position and orientation of a user is acquired, a virtual image is generated based on the data representing the position and orientation of the user, and the virtual image is synthesized with a real image corresponding to the position and orientation of the user. Based on a measurable area of the position and orientation of the user, area data is set. Based on the data representing the position of the user and the area data, notification related to the measurable area is controlled.